Automatic brake



Aug. 4, 1925.

' n. v. MUR THA AUTOMATIC BRAKE Filed Dec. 13, 1924 2 Sheets-Sheet 1 a IQ-aw. I

INVENTOR I7 ii' f 1 20 19 Q Daniel I: 1 4., A'rrokuzf ITNESS AUTOMATIC BRAKE Filed Dec. 15, 1924 2 Sheets -SLeet g Patented Aug. 4, 1925.

1 UNITED STATES DANIEL v. MURTHA, or NEW YORK, N. Y.

AUTTOMATIC BRAKE.

Application filed December is, 1924. Serial no, 755,740.

7 To all whom it may concern: I

Be it known that I, DANIEL V. MURTHA, a citizen of the United States, residing at New York city, in the county of New York and State of New York, have invented new a and useful Improvements in Automatic Brakes, of which the following is a specification.

This invention relates to improvements in automatic brakes for use in connection with dumb waiters or hand operated elevators which are commonly installed in homesand the provision of a device 'which is auto-.

restaurants for hoisting a load from one floor to the other.

The principal object of the invention is niatically operableto preventv a load placed upon a dumb waiter from overbalancing the counterweight when the pull is released from the usual pull rope or when the counter-weight overbalances the load'of the dumb waiter. The device is adapted to check the movement of the dumb waiter at any point in its path of movement. y

Another object of the invention resides in an automatic brake wherein the mechanism is entirely enclosed, but in which access may be readily had should any of the parts require immediate attention.

WVith these and other objects in view, the invention resides in certain novel construction and combination and arrangementof parts, the essential features of which are hereinafter full described, are particularly pointed out in the appended claims, and are illustrated in the accompanying drawing, in which if Figure 1 is a view showingmy invention installed in the shaft of a dumb waiter.

Figure 2 is an enlarged elevation of my Y improved automatic brake.

Figure 3 is a vertical transverse sectiona view on the line 3-3 of Figure 2.

Figure 4 is a transverse sectional view on Figure 5 is a detail perspective view of the hoisting pulley. e

Referring more particularly to the drawing, the reference numeral 10 designates a dumb waiter shaft, 11 the dumb waiter or car movable vertically within said shaft, and 12 the pulley rope which passes over a grooved pulley wheel 13 mounted in the top of the shaft 10. The numeral 14 desig- ,j

nates a hoisting rope or cable, one end of which is fastened to the car 1.1 and the other end supporting a counterweight 15. The rope 14; between its connection with the car and the counterweight passes over a grooved hoisting pulley 16, both the pulleys 18 and 16 being mounted upon a horizontally disposed shaft 17 which shaft is mounted for rotation in bearings 18 adjacent the top M;

end of thedu'mb waiter shaft 10." The-pulley 13 is keyed to the shaft while the pulley 1G is loosely mounted thereon for a purpose to be presently described.

' An annular casing 19 is cast integral with oneof the bearings 18 and has one of its sides open against which the pulley wheel 16 is positioned to provide a closure for the open side of the casing. The pulleywheel 16 is held tight against the casing by a collar V 20 which is fixed to the shaft 17 by a suit able set screw 21. The casing 19 is formed with an annular flange 22 which extends toward the open side of the casing and serves as a brake drum for coaction with a split brake band 28 which fits about the i outer face of the same. 7

The ends of the brake band 23 are disposed adjacent each other and are formed with lugs 24 which extend over the edge of I the flange 22 as shown in Figure 3 of the drawing. Thebrake band is further provided with spaced lugs 25 arranged diametrically opposed lugs 26L and which define a notch 26. i

A plug or collar 27 is fixed to the shaft 17 within the confines of the flange 22 by a suitable setscr ew '28'and is formed with an outwardly extending segment 29 which extends slightly less than half the distance ab t t e shaft- 17. A shoe or plate30 is I arranged over the segment 29. and formed withan arm 31 which is seated in the notch- 7 26 of'the brake band between the lugs 2 5.

'Diametri'cal'ly Opposite the arm 31,,the plate is formed with apair of jaws 32 for? coaction with the'curved faces of the lugs 24 on the free ends of the brake band 23; The central portion of the plate is cut-away .to

receive the se 'ment' 29. and'is formed with shoulders 33 forengagement with the ends the arm 31.

One'side of the pulley wheel 16 is formed with spaced lugs'34 which extend into, the

r1 casing'an'd straddle the arm .31 ofthe plate...

.30 for co -action withthe shoulders 34""during the operation ofthebraking mechanism.

InQoperation, therope 12 is pulled iii-either I fdirection' depending on whether it is desired 7 to Tmove the dumb waiter up or down the shaft which rotates the wheel13 and turn imparts-a rotary movement to the shaft 17 A s the shaft rotates the end of :thesegment 29engages one of the shoulders 83 in the 7 :wheel'16 by reason of the lugs 34 contacting" plate depending on the direction of rotation T of the shaft which causes the plate and brake band23 to also rotate and which plate imparts a rotary movement to the hoisting the houlders 84E, It will therefore be seen that the hoisting pulley wheel will rot'ate, when the pulley l3is rotated by reason of the rope=l2 and will cause the hoist ng rope to liftor lower the car as the occasion mand v We shall nowpresume thata'load is placed upon theicar and whichis of a greater or less-weight than the counterweight, and the pulley ropeis left free. The weight of such "load will in, the event ,7 thatthe loadoverbalances the counterweighuor if the coun terweight overba-lances thev load, rotate the pulley 16 causing one of the lugs 341to*en gage-one: of the shoulders34, of the plate er the force appliedtothe wheel 16 to'rotate the same the greater will be thebraking ac:

causing the plate to move whereby the jaws 32set up a wedging action with the lugs 24 ontthe end of the bra-kebandithereby causing the brake band tobe contracted about the ffiange or drum 22 of the casing and which casing is rigidly secured to the supporting structure. It will now be seen that the greattion betwee'nthe brake band and the drum. When the pressureis relieved from the pulley, the brake band will automatically expand thereby'breaking its grip on the drum .due to the normal tendencyof thejband to expa d- From the foregoing description, it will be seen that I have provided a brake which is au'tomaticfin its vactionfor supporting a car invario'us planes ofelevation and wherea novel and attractive manner.

dependent of said shaft. r

iiithe'mechanism for performing this func- 7 tion is exceedingly"simple' 'andis enclosed in tion, it is obvious that many. of the details may be varied without in any way departing fore do not limit myself to the exact details of construction hereinset forthnor. to anythin-g less than the whole of-myi'nvention limited only by the appended claims.

What isclaimed as new is e 1L In a devic eofthe class described, the

combination with a stationary casing, a ro- 'tatable' shaft having one of its bearings I I deem to be] the most desirable embodiment ofmyiinvenfrom the spirit of my invention, and Ithere- I i therein, an annular drum arranged within fsaid'casing, a split band encircling said I drum and normally free .to rotate about sald drum, a collar fixed to said shaft, a pulley means betwee n'said collar and said pulley wheel to move with said shaft upon rotation of the same, said means including a member havingshoulders for co-action with lugs ex tendingfi'om said pulley wheel.

'wheelfiloosely mounted on said shaft,.and

"wheel for causing said band and pulley- '2. Ina-device of theclass described,.the l combination with a stationarycasing, arotatable shaftv extending therethro ugh, an'annular. drum arranged within. said casing, a split band encircling said drumfand nor mally free to rotate about said drum, acolr l ar; keyed to "said shaft. a pulley wheel loosely mounted'on'said shaft, a.ncl means be; tween, said collar and-said pulley wheel} for causing said band .and pulley wheel to move" with'said'shaftfupon rotation of the same,

and'means automatically operableupon the rotation of said-pulley wheel independent of saidsliaft for'moving said split band into frictional binding action with said. drum to lock said pulley rwheel-iagainst rotation in either direction, 1 I t 3. Ina devicefofthe class described, the combination of av stationary casing, a :rotatable shaft 'having one of its bearings therein, 7

an annulardl'um formed, on the sidewall of' saidcasing within thesame, a splitresilient 'bandenci-rclingsaid drum, acollar fixed to saidshaft, a member,; aws on said member for co-ac'tionwith the free ends of said split i band, shou'lderson said .member" for/co I action with a portion of said'collaruponthe rotation of said shaft apulley wheel loosely mounted on .said shaft,- and-means on said pulley? Wheel, for coaction with said memher for moving said member to cause said jaws to compress the free endsof said split band to. contract said band about said drum upon the movement of said pulley wheelin- .4. In a device of the class described,-the

combination of a"stationarycasing open at one slde, a rotatable shaft having one of its bearings therein, an annular drum formed casing to close the same,- and means on said f on the side wall of said casing within the pulley Wheel for co-action with said memsame, a split resilient band encircling said her for moving said member to cause said drum, a collar fixed to said shaft, a member, jaws to compress the free ends of said 5. jaws on said member for co-action with the split band to contract said band about said 1 free ends of said split band, shoulders on drum upon the movement of said pulley said member for co-action with a portion of Wheel independent of said shaft. said collar upon the rotation of said shaft, In testimony whereof I have affixed my a pulley wheel loosely mounted on said shaft signature.

10 and disposed against the open side of said DANIEL V. MURTHA. 

